1. Field of the Invention
The present invention relates to a fluid-filled type vibration damping rubber device which may be widely used, such as in an engine mount and a suspension bushing for an automobile, a vibration damping member for an industrial machine, and the like.
2. Description of the Related Art
Vibration damping rubber members, such as an engine mount and a suspension bushing, which are used as connecting members between various components of an automobile, such as an engine and a frame, express vibration damping performance by virtue of, for example, a spring characteristic and a vibration attenuation characteristic exerted by a rubber body (vulcanized rubber molded body). In recent years, various fluid-filled type vibration damping rubber devices have been proposed, which have further improved the vibration damping performance by filling the vibration damping rubber member with a fluid (see, for example, JP-A-SHO-63-83426, JP-A-SHO-64-51488, and JP-A-HEI-5-140579).
The fluid-filled type vibration damping rubber device includes chamber walls, which deform in accordance with vibration and are each made of a rubber body, and an enclosed space formed by the chamber walls is filled with a filling fluid such as ethylene glycol. In addition, the rubber body generally contains an antioxidant, a vulcanization accelerator, and the like in order to improve rubber characteristics (in particular, heat resistance and permanent set resistance).
However, in the fluid-filled type vibration damping rubber device as described above, components, such as the antioxidant, in the rubber body constituting each of the chamber walls for fluid filling dissolve into the filling fluid in some cases owing to ambient temperature, the passing of time, endurance use, or the like. In addition, when such dissolution of the antioxidant or the like occurs, there is a risk that the rubber body could become degraded and its durability could deteriorate.